Electrodeposition of nickel

ABSTRACT

Bright nickel plating baths comprising aqueous nickel salt solution containing a sulfonated ester reaction product of maleic acid and acetylenic alcohol as a brightener.

United States Patent Merker et al.

[451 May 20', 1975 ELECTRODEPOSITION OF NICKEL Inventors: Reuven Merker,Englewood Cliffs; Salvatore Lucca, Paramus, both of Assignee: TheMetalux Corporation, Paterson,

Filed: Aug. 17, 1973 Appl. No.: 389,379

U.S. Cl. 204/49 Int. Cl. C23b 5/08; C23b 5/46 Field of Search 204/49, 43T, 43 N, 43 P;

Primary ExaminerG. L. Kaplan [57] ABSTRACT Bright nickel plating bathscomprising aqueous nickel salt solution containing a sulfonated esterreaction product of maleic acid and acetylenic alcohol as a brightener.

12 Claims, No Drawings ELECTRODEPOSITION OF NICKEL This inventionrelates to compounds useful as additives to nickel electroplating bathsand more particularly to the electrodeposition of smooth, lustrousdeposits of nickel from baths containing these additives.

BACKGROUND OF THE INVENTION Brighteners are added to nickel platingbaths, including the commonly used Watts-type acid bath, to increase theleveling characteristics and to produce bright nickel electrodeposits.The use of unsaturated molecules containing alkyne groups has beensuggested. While compounds such as l,4-butyne-diol andl,4-bis(hydroxyethoxy) butyne produce some degree of improvement in theplating bath, uniform results are difficult to achieve. Thesedeficiencies are readily evident in plating baths operated attemperatures above 50C. Many commercial products have complex shapeswhich dictate that the nickel be deposited in certain areas of lowcurrent density. Accordingly, there exists a need for nickel platingbaths in which irregularly shaped objects may be nickel electroplatedwith a uniform lustrous and bright nickel deposit. Such desirableelectrodeposits must be made in the recesses of the object as well as inthe elevated areas.

As stated above, acetylenic compounds tend to produce a cloudy haze onthe deposited nickel surface, especially in high concentrations underthe abovementioned bath temperatures. This is stated clearly in U.S.Pat. No. 3,378,470 (col. 1, lines 30ff.) where it can be read thatacetylenic alcoholic brighteners produce a cloudy haze on the nickeldeposit which is most evident in those areas at which nickel isdeposited under conditions of low current density. Furthermore,acetylenic compounds have the tendency to skip plate" and to impairductility as clearly stated in U.S. Pat. No. 3,133,006 and in U.S. Pat.No. 3,305,461. Also, the acetylenic compounds mentioned in thesepatents, when present in a nickel plating solution, render it verysensitive to metallic contamination by impurities such as zinc, copperand iron. The acetylenic-olefinic esters disclosed in U.S. Pat. No.3,378,470, while appearing superior to other prior art additivecompounds, nevertheless are quite sensitive to metallic contaminationand, furthermore, suffer the disadvantage of becoming quiteunsatisfactory when utilized in amounts exceeding their optimumconcentrations.

It is therefore an object of the present invention to overcome cloudydeposits, haze, skip plating, metallic contamination and limitations inconcentration, by providing a novel heretofore unknown group of platingadditives, as more fully described hereinbelow.

DETAILED DESCRIPTION OF THE INVENTION This invention, accordingly,provides acetylenicolefinic ester sulfonates prepared by thecondensation of acetylenic alcohols and maleic acid followed bysulfonation, which are particularly suitable as additives in aqueousacidic nickel electroplating baths to produce superior lustrous nickelelectrodeposits. Nickel may be electrodeposited from such bath over awide range of current densities, including regions of low currentdensity now considered too low to obtain desirable electrodeposits.There is also a marked improvement in brightness and ductility, which isuniform throughout the nickel electrodeposit.

The desired a'cetylenic-olefinic ester sulfonates are prepared by firstreacting maleic acid with acetylenic alcohols and diols, as fullydescribed in U.S. Pat. No. 3,378,470, and having the formula and nis 0,l, or 2; and n must be 0 when R is hydrogen methyl. Illustrative ofthese acetylenic alcohols and diols are propargyl alcohol;l-hydroxy-butyne-2,3; l,4- butynediol; and bis(hydroxyethoxy) l,4-butyneand higher ethylene oxide adducts of l,4-butynediol. The olefinicdicarboxylic acid reactant in the preparation of the acetylenic-olefinicesters is maleic acid or such equivalent olefinic acid compounds asmaleic anhydride, and the alpha, beta-olefinic dicarboxylic acidscontaining up to about 8 carbon atoms in the chain. Subsequently, thereaction product is sulfonated in accordance with well known sulfonationtechniques, known to any person skilled in the art. Typically, theradical SO Na is introduced in the broken carbon double bond.

The composition of the acetylenic-olefinic esters is dependent upon thespecific acetylenic compound and acid utilized and the relativeproportions of each, and also is influenced by the reaction conditions.The products of the final sulfonation reaction may be mixtures of estersulfonates as will be apparent.

The products of the reaction of maleic acid and an acetylenic monoalcohol will be a monomeric ester which may be (a) a monoester formedesterification of only one of the acid groups of the maleic acid by onemolecule of the alcohol, or, (b) a diester formed by esterification ofboth of the acid groups of the maleic acid by two molecules of thealcohol. Reaction of an acetylenic diol and the dicarboxylic acid mayresult in a variety of reaction products of a monomeric and polymericnature. The reaction products may be mixtures of several of thesepolyesters. The reaction conditions utilized vary somewhat dependentupon the acetylenic alcohol reactant. Where it is a liquid and used inexcess, it is often useful to dissolve the maleic acid in the alcoholand heat to temperatures up to about C., where such temperature is notabove the temperature at which the reactants volatilize under thereaction conditions. It is often desirable to carry the reaction out ina solvent which is inert to the reactants and reaction products. Suchreactions are preferably carried out under reflex conditions. Maleicanhydride is often the preferred acid reactant instead of maleic acid.When used herein, it is understood that terms are used alternativelyreferring to these compounds which are equivalents for purposes of thisinvention. The following compounds are illustrative of theacetylenic-olefinic ester sulfonates of the invention: Compound no:

Co -pound no;

CE 3 CCl-l 0C(0 SO Na 3 SO Na 3 -Continued T-IOCP2CH2OCH2 2 on F c H ccao c (0)0 2 ICHC(O)OH SO Na SO Na 3 (6) HOCHZCHZO CH C CCH OCH CH 000ll-I NaSO-CH OCHZC 2 CCHZOCH CH OCO CH HOCH 2 ECCH OC(O)CH CH0 0 OH soNa 3 H c (8) Ho(o)ccH (EHC(O)OCH2CF2OC 2 NaSO.

ECCH OCH CF 00 0 CH -CHC 0 OF so N 3 9. (9) HC ccH oc(oms -encwmcn czcsSO Na 3 The acetylenic-olefinic ester sulfonates, if containing terminalacid or hydroxy groups may be used in the form of the corresponding saltwith such cations as nickel, sodium, potassium, lithium, or magnesium.

The brighteners in accordance with this invention are useful in acidnickel baths which usually contain nickel sulfate and/or nickelchloride. The Watts-type acid baths are most commonly employed.Generally, the ph range of these acid baths is between 2.5 to 5.0, andthe temperature range is between about 35C and 70C. The concentration ofthe acetylenic-olefinic ester sulfonates in the bath, usually between0.001 and 1.0 gram/liter (g./l. for economic reasons, ned not be limitedto these amounts, but may be employed in any excess desired. This is oneof the most important advantages of the compounds of this invention,namely, the elimination of harmful effects regardless of theconcentration of ester sulfonate employed.

The acetylenic-olefinic ester sulfonates may be used with auxiliarybrighteners such as the aromatic and aliphatic unsaturated sulfonicacids, sulfonamicles, and sulfonimides. They may, however, be employedas a brightening additive in electroplating baths which do not containother additives. In addition to the baths discussed hereinbefore whichcontain nickel sulfate and- /or nickel chloride, these sulfonatecompounds may also be employed in nickel plating baths containing thesulfamate anion.

The acetylenic-olefinic ester sulfonates are most commonly used inconjunction with the following sulfonimides and sulfonamides: benezenesulfonamide; ortho-toluene sulfonamide; para-toluene sulfonamide;Saccharin, sodium salt; metabenzene disulfonamide; allylsulfonamide; andvinyl benzenesulfonamide. Other sulphur compounds which may beincorporated in the baths are benzenesulfonic acid; allyl sulfonic acid;para-vinylbenzene sulfonic acid; 1,5-naphthalene sulfonic acid; and1,3,6-naphthalene sulfonic acid. These compounds may be added as thespecified compound per se and used in amounts between about 0.1 and 15g./l. Those compounds containing salt-forming groups may be added in theform of their nickel, sodium, potassium, or magnesium salt.

The following are specific examples of aqueous acidic nickelelectro-plating baths containing the acetylenic-olefinic estersulfonates of the invention. Bright, lustrous nickel electrodepositswere obtained over a wide current density range from these bathsregardless of compound concentration. The acetylenicolefinic estersulfonates are identified by the compound N0. specified hereinbefore.

Examples l-3: G./l. NiSO 6H O 300 NiCl 6H O 45 Boric Acid 45 Saccharin 1Bromobenzene sulfonic acid 1 Compd. N0. 3, respectively: 0.08, 0.32, 0.8Sodium lauryl oxyethyl sulfate 1.0 Temperature, C. 60 pH, 4.0

Examples 4-6:

NiSO 6H O 200 NiCl 6H O 100 Boric Acid 45 Naphthalene trisulfonic acid 5Compd. No. 8, respectively: 0.l, 0.3, 0.9 Temperature, C. 60 pH, 4.0

Examples 7-9:

NiSO 6l-l O 300 NiCl 6H O 45 Boric acid 45 Saccharin i lToluenesulfonamide 0.5 Compd. No. 2, respectively: 0.05, 0.2, 0.5 Sodiumlauryl sulfate 9.50 Temperature, C. 50-55 pH, 3.5-4.5.

Examples l0-l2:

NiSO ,6H O 250 NiCl 6H O Saccharin l.0 Vinyl benezenesulfonic acid 1.0Compd. No. 5, respectively: 0.05, 0.2, 0.4

Sodium octyl sulfate 0.5 Temperature, C. 45 pH, 4.0

Examples l3-l5:

NiSO46H O 25 NlClzGHzO 250 Boric acid 45 Saccharin 1.0 Benzenedisulfonate 10.0 Compd. No. 1, respectively: 0.08, 0.32, 0.8

Temperature, C. 45

The aqueous acidic nickel electroplating baths conthe unique property ofproducing nickel electrodeposits of high and uniform luster in areas ofboth high and low current density regardless of concentration, contraryto non-sulfonated esters. This is attributed to the effects of thesesulfonates as additives. These additives were found to be more effectivein this respect than the acetylenic alcohols or diols or the esters fromwhich they are derived.

Examples 16-18 (bath same as exam les 13-15):

Compd. CH: CCH OC(O)CH=CH(O)OH a. Concentration 0.08 0.08

Result good good b. Concentration 0.16 0.16

Result good haze c. Concentration 0.32 0.32

Result good spots. skips wherein R is selected from the group consistingof hydrogen, H C, and HO(CH CH O),.CH n is 0-2,

and n is 0 when R is hydrogen or H C.

2. The nickel plating bath of claim 1 containing between about 0.1 and15 g./l. of at least one organic sulphur compound selected from thegroup consisting of aromatic and aliphatic unsaturated sulfonic acids,aromatic sulfonamides, and sulfonimides.

3. The bath of claim 2 containing the sulfonated ester reaction productof one mole of l,4-bis( hydroxyethoxy) butyne with one mole of maleicacid. I

4. The bath of claim 2 containing the sulfonated ester reaction productof one mole of l,4-bis(hydroxyethoxy) butyne with two moles of maleicacid.

5. The bath of claim 2 containing the sulfonated ester reaction productof one mole of 1,4-butynediol with two moles of maleic acid.

6. The bath of claim 1 containing between about 0.1 and 1.0 g./l. ofsaid ester.

7. The bath of claim 1 wherein said ester sulfonate is the sulfonatedreaction product of one mole of propargyl alcohol with one mole ofmaleic acid.

8. The bath of claim 1 wherein said ester sulfonate is the sulfonatedreaction product of one mole of 1,4- butynediol and with one mole ofmaleic acid.

9. The bath of claim 1 wherein said ester sulfonate is the sulfonatedreaction product of one mole of l.4-bis(hydroxyethoxy) butyne with onemole of maleic acid.

10. The bath of claim 1 wherein said ester sulfonate is the sulfonatedreaction product of one mole of 1,4- butynediol with 2 moles of maleicacid.

11. The bath of claim 1 wherein said ester sulfonate is the sulfonatedreaction product of one mole of 1,4-bis(hydroxyethoxy) butyne with 2moles of maleic acid.

12. The process of electrodepositing bright nickel which compriseselectrolyzing an aqueous acidic solution comprising a nickel salt and atleast about 0.001 g./l. of'an ester sulfonated reaction product ofmaleic acid and an acetylenic alcohol having the formula wherein R isselected from the group consisting of hydrogen, H C, and HO(CH CH O),,CHis 0-2, and n is 0 when R is hydrogen or H C.

1. A BATH FOR PRODUCING BRIGHT NICKEL ELECTRODEPOSITS COMPRISING ANAQUEOUS ACID SOLUTION OF A NICKEL SALT AND AT LEAST 0.001 G./L. OF ASULFONATED ESTER REACTION PRODUCT OF MALEIC ACID AND AN ACETYLENECALCOHOL, SAID ALCOHOL HAVING THE FORMULA
 2. The nickel plating bath ofclaim 1 containing between about 0.1 and 15 g./l. of at least oneorganic sulphur compound selected from the group consisting of aromaticand aliphatic unsaturated sulfonic acids, aromatic sulfonamides, andsulfonimides.
 3. The bath of claim 2 containing the sulfonated esterreaction product of one mole of 1,4-bis(hydroxyethoxy) butyne with onemole of maleic acid.
 4. The bath of claim 2 containing the sulfonatedester reaction product of one mole of 1,4-bis(hydroxyethoxy) butyne withtwo moles of maleic acid.
 5. The bath of claim 2 containing thesulfonated ester reaction product of one mole of 1,4-butynediol with twomoles of maleic acid.
 6. The bath of claim 1 containing between about0.1 and 1.0 g./l. of said ester.
 7. The bath of claim 1 wherein saidester sulfonate is the sulfonated reaction product of one mole ofpropargyl alcohol with one mole of maleic acid.
 8. The bath of claim 1wherein said ester sulfonate is the sulfonated reaction product of onemole of 1,4-butynediol and with one mole of maleic acid.
 9. The bath ofclaim 1 wherein said ester sulfonate is the sulfonated reaction productof one mole of 1,4-bis(hydroxyethoxy) butyne with one mole of maleicacid.
 10. The bath of claim 1 wherein said ester sulfonate is thesulfonated reaction product of one mole of 1,4-butynediol with 2 molesof maleic acid.
 11. The bath of claim 1 wherein said ester sulfonate isthe sulfonated reaction product of one mole of 1,4-bis(hydroxyethoxy)butyne with 2 moles of maleic acid.
 12. The process of electrodepositingbright nickel which comprises electrolyzing an aqueous acidic solutioncomprising a nickel salt and at least about 0.001 g./l. of an estersulfonated reaction product of maleic acid and an acetylenic alcoholhaving the formula RC*CC(H2)(OCH2CH2)nOH wherein R is selected from thegroup consisting of hydrogen, H3C-, and HO(CH2CH2O)nCH2-, is 0-2, and nis O when R is hydrogen or H3C.